Justification:
This species is listed as Least Concern in view of its wide distribution, presumed large population, occurrence in a number of protected areas, tolerance to some degree of habitat modification, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.

This species has a circumboreal, Holartcic distribution, taking in much of Europe and North Africa, Asia and northern North America. It has been introduced in New Zealand, Malta, Crete, the Azore Islands, and apparently also Sao Tome off west Africa (Sheffield and King 1994). It is found throughout Europe and on many islands, including the Azores, Britain (but not Ireland), and all major Mediterranean islands. The populations on the Azores and Mediterranean islands (Malta and Crete) are widely considered introduced (Dobson, 1998; McDonald pers. comm.). It is also found on Honshu, Hokkaido, Kunashiri, Etorofu, and Sakhalin Islands in Japan (Abe et al., 2005) and northern Mongolia (Bannikov, 1954; Dulamtseren, 1970).

In the European part of its range, there are documented population declines in some areas (e.g. Britain: Battersby, 2005), and suspected declines in others. Although it has a wide distribution, it is considered rare in North America (Sheffield and King, 1994). In Eurasia, it is relatively common, but not often seen (Sheffield and King, 1994). Local densities of 0.2 to 1.0 individuals per hectare can occur in favored habitats when prey are abundant (Sheffield and King, 1994). However, over wider areas, the average density may be as low as 1 to 7 per 100 hectares (Goszczynski, 1977). Populations fluctuate both seasonally and annually, sometimes involving large increases of up to 10-fold, concurrently or within 9 months of a population peak of small rodents, and lasting 6 to 18 months (Sheffield and King, 1994). Thought to be rare (though sometimes locally fairly common) throughout the range in the southeastern U.S., but actual status is uncertain (Handley 1991).

Weasels tolerate a wide range of habitats, including forests, farmlands and cultivated fields, grassy fields and meadows, riparian woodlands, hedgerows, alpine meadows and forests, scrub, steppe and semi-deserts, prairies, and coastal dunes (Sheffield and King, 1994; Pulliainen, 1999). This species occurs from sea level to at least 3,860 m. It forms dens in crevices among tree roots, in hollow logs, or in abandoned burrows of other species. This species is a specialist diurnal predator of small mammals (especially rodents), although it will also occasionally feed on birds’ eggs, lizards, frogs, salamanders, fish, worms, and carrion (Sheffield and King, 1994). Food may be stored for the winter (Danzig, 1992). Habitat selection is usually determined by local distribution of rodents. Foraging individuals avoid open spaces, where they are most vulnerable to predation by raptors (Sheffield and King, 1994). They prefer dense, rank grassland where microtines (voles and lemmings) are abundant (McDonald pers. comm.).

Threats include incidental poisoning with rodenticides (Sheffield and King, 1994) and persecution. The weasel prefers open agricultural habitats, which are declining owing to changes in agricultural practices (rural abandonment) in parts of Europe, as open fields undergo succession.

This species is found in many protected areas. It is listed on Appendix III of the Bern Convention (Pulliainen, 1999), and is protected under national and sub-national legislation in a number of range states (e.g. Sichuan, China: Yi-Ming et al., 2000). Monitoring is required to quantify the population trend in Europe.